The present invention relates to a pipe bender, which has a shaft, a movable arm and a fixed arm. The movable arm is movable with the shaft in order to bend a pipe positioned between the movable arm and the fixed arm.
Referring to FIG. 6, a heretofore known pipe bender comprises a covering 11, a shaft holder 12, a shaft 13, a movable arm 14, a fixed arm 15 and a transmission combination 16.
The transmission 16 is arranged in the covering 11, and has an oil cylinder 161. The oil cylinder 161 has one end connected to a chain 162, and the other end connected to a chain 163. The chains 162,163 wind around a first wheel 164 and a second wheel 165 respectively, and then connect a connecting rod 166.
Referring to FIG. 7, the oil cylinder 161 makes the shaft 13 turn in order to move the movable arm 14 relative to the fixed arm 15. Thus, the movable arms 14 and the fixed arm 15 can bend a pipe located in between.
The process and fastening means for locating a pipe to the fixed arm and the movable arm are not a subject of the present invention, so they are not detailed here.
From the above description, it can be seen that the pipe is bent by means of the cylinder driving the first wheel 164. Therefore, the wheel is made to have a circumference as big as possible in order for the pipe bender to have more power. However, the size and the cost of the pipe bender will increase when the wheel is big, i.e. the pipe bender is less cost-effective.